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Zheng et al. Soft Sci. 2026, 6, 32 Page 47 of 57

three-dimensional interconnected conductive structures between layers, greatly enhancing the rate
performance of fiber electrodes. Conductivity is improved by orders of magnitude when carrier
concentration is further increased by chemical doping (e.g., K, Br ) [181-183] . Graphene/MXene composite fibers
2
show great cycling stability and high volumetric capacitance as electrode materials. For example, Li et al.
built Ti CNT //rGO asymmetric supercapacitors with very low self-discharge rates and an energy density of
3
x
19.7 mWh·g -1[184] . Xie et al. reported rGO/MXene fibers achieved an areal capacitance of 1,180 mF·cm -2
[Figure 15G] and a wide voltage window of 0-1.6 V in zinc-ion hybrid supercapacitors .
[178]

Shen et al. used a wet spinning technique to successfully create vertically aligned MXene/PEDOT:PSS/rGO
composite fibers while carefully regulating the spinning slurry’s rheological characteristics. M PG was the
y
x
designation given to these fibers, where x and y stand for the mass percentages of MXene and GO,
respectively. An ideal compromise between mechanical strength and electrical conductivity was found when
the MXene content reached 42% (mass fraction) (M PG ) when the PEDOT:PSS content was fixed at 20%
42
38
(mass fraction) and the MXene-to-GO mass ratio was systematically adjusted. The spinning slurry showed
near-Newtonian fluid behavior at this composition. Rapid ion transport was made possible by the
nanosheets being reoriented perpendicular to the fiber axis by strong stretching at the nozzle exit. This
resulted in a vertically aligned structure with ordered interlayer spacing (~40 nm). Two M PG fibers were
38
42
arranged in parallel on a polyethylene terephthalate (PET) substrate, coated with a PVA/LiCl gel electrolyte,
and set up as a symmetrical dual-electrode system for the supercapacitor assembly. The device functions
steadily within a broad potential window of 2 V, which is twice the breadth reported for the majority of
fiber-based supercapacitors. It reaches a volumetric capacitance of 150 F·cm at a current density of 0.1
-3
A·cm . Thus, it provides a very high volumetric energy density of 100 mWh·cm at a power density of 100
-3
-3
mW·cm , as illustrated in Figure 15H. Furthermore, the device maintained exceptional low-temperature
-3
performance at -40 °C with an energy density of 16 mWh·cm by grafting nanoscale AgI solid electrolyte
-3
onto the fiber surface using Co -ray irradiation. This work validates the viability of MXene/graphene
60
γ
composite fibers as wearable energy storage devices in harsh environments by offering a paradigm for
balancing mechanical and electrochemical properties .
[177]
Moreover, composite and hybrid approaches turn fibers from passive conductive materials into
multipurpose smart response platforms with features like electromagnetic shielding, energy conversion and
management, and environmental monitoring. For example, the construction of highly sensitive humidity
sensors is made possible by combining the high conductivity of MXene with the humidity sensitivity of
graphene; the development of low-voltage-driven or light-responsive wearable heating fabrics is made easier
by utilizing their superior electrothermal and photothermal effects. Wang et al.’s MXene/cellulose composite
microfibers with graphene aerogel interpenetrating network simultaneously achieve thermal insulation,
[185]
hydrophobicity, and broadband microwave absorption (effective absorption bandwidth up to 10.4 GHz),
suggesting potential uses in multifunctional textiles. Fiber supercapacitors can demonstrate exceptional
low-temperature performance in severe situations by using composite solid-state electrolytes (such as AgI),
which maintains effective energy output at -40 °C and expands their application prospects in wearable
devices for harsh environments .
[177]
Future efforts should concentrate on precisely controlling multi-component interface structures, ensuring
structural consistency during large-scale fabrication, and balancing high conductivity with superior
mechanical properties, even though composite and hybrid strategies greatly improve the overall performance
and functional integration of fibers. Graphene/MXene composite fibers have the potential to advance the
next generation of smart textiles toward high performance, multifunctionality, and significant environmental
adaptability through interdisciplinary material design and engineering methodologies.